<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        var a =10;
        ++a;
        var b = ++a +2;
        console.log(b);//14

        var c = 10;
        c++;
        var d = c++ +2;
        console.log(d);//13

        var e = 10;
        var f = e++ + ++e;
        console.log(f);//22
        //后置自增 先表达式返回原值 后面变量在自加1
    </script>
</head>
<body>

</body>
</html>